journal of dentistry 42 (2014) 1248–1254

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Longevity of posterior restorations in primary teeth: Results from a paediatric dental clinic Gabriela Dos Santos Pinto a, Luı´sa Jardim Correˆa Oliveira a, Ana Regina Romano a,b, Lisandrea Rocha Schardosim b, Maria Laura Menezes Bonow a,b, Marcos Pacce b, Marcos Britto Correa a, Fla´vio Fernando Demarco a,c,*, Dione Dias Torriani a,b,* a

Post-Graduate Program in Dentistry, Federal University of Pelotas, Pelotas, Brazil Department of Social and Preventive Dentistry, School of Dentistry, Federal University of Pelotas, UFPel, Pelotas, RS, Brazil c Post-Graduate program in Epidemiology, Federal University of Pelotas, Pelotas, Brazil b

article info

abstract

Article history:

Objectives: The aim of this retrospective study was to evaluate the longevity of restorations

Received 29 March 2014

in the posterior primary teeth of children attending to a public paediatric dental clinic and to

Received in revised form

test the factors associated with failures.

9 July 2014

Methods: Patient records of 329 children (162 boys and 166 girls) were used for collecting and

Accepted 12 August 2014

analyzing data. A total of 565 restorations in primary teeth were included in the study. All children enrolled in the study were classified as high caries risk. The longevity of restorations from their placement until failure (up to 4 years of follow-up) was assessed using the

Keywords:

Kaplan–Meier survival curves with log-rank test. Multivariate Cox regression analysis with

Longevity

shared frailty ( p < 0.05) was used to assess the factors associated with failures.

Posterior restorations

Results: Up to 4 years of follow-up, the annual failure rates were 9.5% for composite fillings,

Resin composite

12.2% for light-cured glass ionomer restorations, and 12.9% for conventional glass ionomer

Primary teeth

restorations with statistical difference between the materials ( p = 0.014). Glass ionomer

Glass ionomer cements

restorations had a higher risk of failure over time compared with composites (HR 1.86, 95%

Survival

CI 1.17–2.97). In crude analysis, Class II restorations showed lower survival rate than Class I restorations ( p = 0.031) but lost significance after adjustments. Conclusions: Our findings suggested that the material influenced the survival rate of primary posterior restorations, with composite presenting the best performance. Clinical significance: Differences were observed between restorative materials with different properties in primary teeth up to 4 years of follow-up. This study provides valuable information regarding the primary teeth posterior restoration longevity in a paediatric population with restorations performed under daily life clinical environment. # 2014 Elsevier Ltd. All rights reserved.

* Corresponding authors at: Post-Graduate Program in Dentistry, Federal University of Pelotas, R. Gonc¸alves Chaves, 457, 5th floor, CEP 96015-560 Pelotas, RS, Brazil. Tel.: +55 53 32256741x130; fax: +55 53 32256741x130. E-mail address: [email protected] (F.F. Demarco). http://dx.doi.org/10.1016/j.jdent.2014.08.005 0300-5712/# 2014 Elsevier Ltd. All rights reserved.

journal of dentistry 42 (2014) 1248–1254

1.

Introduction

Although a decrease in caries prevalence has been observed worldwide, the placement of restorations, especially in posterior teeth is frequent in dental offices.1,2 Amalgam restorations were used in the past but, nowadays, have been replaced by restorations with adhesive properties to reduce the amount of the remaining tooth structure removed and increase the strength of the remaining.3 The longevity of direct posterior composite restorations is well established for permanent teeth.4–6 The size of the cavity, the caries, and occlusal risks are some factors that affect significantly composite restoration survival.5,7 However, the placement of restoration in carious deciduous teeth and the longevity of these restorations are still under discussion.8 In addition, the loss of deciduous teeth by dental caries can cause malocclusion because of the wasted space.9 Thus, the restoration of decayed primary teeth could be an option to solve these problems. Besides composite resin, another tooth-coloured direct materials used in posterior teeth are the resin modified glass ionomer cements (RMGIC) and conventional glass ionomer cements (GICs). Although in permanent teeth, the performance of glass ionomer products is inferior to composite,10 there are few studies comparing the performance of RMGICs and GICs to composite restorations in primary teeth, with controversial results,11–13 and most of the available studies were randomized clinical trials performed under optimal condition. Because of relatively lack of data available on the longevity of restorations in the primary dentition, it would be important to investigate the longevity of different materials used to restore posterior primary teeth in conditions closer to the clinical daily life. Thus, this study aims to evaluate the survival of restorations performed by fourth year dental undergraduate students, with different materials in posterior primary teeth in children with high caries activity treated in a paediatric dental clinic, and to assess factors associated with failure.

2.

Methods

The research protocol (12/2013) was approved by the Research Ethics Committee, School of Dentistry, Federal University of Pelotas, Brazil. A retrospective longitudinal study was conducted. The target population consisted of children assisted in the Paediatric Clinic of the School of Dentistry, Federal University of Pelotas, which were seen during the year 2012. This clinic offers free dental care and assists mainly patients with low familiar socioeconomic status. The children were assisted by fourth year dental undergraduate students, closely supervised by professors, who are specialists in Paediatric Dentistry. All the information used in this study was collected from clinical records. Permission to use patient data was obtained through the informed consent form by parents or legal guardians at the first dental visit. To be included in the study, children should have received at

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least one restoration (Class I or Class II) in a posterior primary teeth between 2009 and 2012. In addition, patients should have at least one visit at the clinic after the placement of the restoration.

2.1.

Restorative procedures

Restorative material included in the study was composite resin (Charisma – Heraeus Kulzer, Hanau, Germany, Herculite XR – Kerr, Orange, CA, USA and Z100 – 3M ESPE, St. Paul, MN, USA), RMGICs (Vitro Fil LC – DFL, Rio de Janeiro, Brazil), and GICs (Vitro Fil – DFL, Rio de Janeiro, Brazil). Although some procedures were performed under rubber dam, most of the restorations were placed under relative isolation, using cotton rolls and saliva aspirator to avoid direct contact of the restorative procedure with the saliva. Cavities were prepared with low-speed drills and dentine excavators for caries removal and high-speed carbide burs for removing enamel and unsatisfactory restorations when necessary. Preparation was restricted to removal of caries. In very deep cavities, the region close to the pulp was protected with calcium hydroxide cement (Hydro C; Dentsply, Petro´polis, RJ, Brazil). Composite restorations were restored using etch-andrinse adhesive systems. Dentine and enamel were etched with 37% phosphoric acid gel and covered with the adhesive system Adper Single Bond 2 (3M ESPE, St. Paul, MN, USA). RMGICs and GICs were handled following manufacturer’s recommendations. For all restorations, finishing and polishing were performed using fine-grained diamond burs, sandpaper strips, and siliconized tips with a paste of aluminium oxide.

2.2.

Data collection and variables

The information evaluated included individual and toothlevel variables. Demographic (sex), socioeconomic, and oral health variables were included at individual level. Mother’s school level was collected in years and dichotomized (up to eight years of formal education or more than eight years). Dental caries experience was assessed by dmft index (WHO, 1997) and categorized in quartiles. Then, three lower quartiles were considered as ‘‘moderate caries group’’ (dmft 0–8), and high quartile was considered as ‘‘high caries group’’ (dmft greater than 8). The variable ‘‘pulp intervention’’ was collected in dichotomous form (‘‘yes’’ when child had undergone to at least one endodontic intervention during the time of treatment and ‘‘no’’ when child had not undergone endodontic intervention). At the tooth level, the variables collected were the restorative material used in restorations (CR, RMGIC, and CGIC – CIV) and type of cavity (Class I, when only the occlusal surface was involved, or Class II, with two or more surfaces involved, including a proximal surface or cavities only involving the proximal surface). The outcome of the study was the failure of posterior restorations in primary teeth. Failures were assessed by checking the records of the patients and were considered in the presence of loss of restoration or fracture requiring a reintervation (restoration repair or replacement) or symptoms requiring pulp intervention or tooth extraction.

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2.3.

journal of dentistry 42 (2014) 1248–1254

Statistical analysis

Data collected from patient records were included in a database and analyzed using software Stata 11.0. For survival analysis, the time between the placement of the restoration and the failure event (when occurred) or the last visit to the clinic was considered. Children attend regularly to paediatric clinic since the exfoliation of their primary molars. Restorations were censored of the analysis when teeth have exfoliated. Survival analysis included the Kaplan–Meier survival curves. Survival curves were drawn for different materials, different types of cavities, caries experience of patients, and comparison between patients with and without pulp intervention. The log-rank test was used to compare survival curves. The factors associated with failure were analyzed using multivariate analysis utilizing Cox regression models with shared frailty, which considers that observations within the same group (the patient) are correlated, sharing the same frailty. This model for survival analysis is analogous to the multilevel regression models with random effects, therefore considering the correlation intragroup. Only variables presenting a p  0.250 were included in the final model. Hazard ratios (HR) and their 95% confidence intervals were estimated. For all analyses, a significance level of 5% was considered.

3.

Results

The distribution of restorations according to individual and tooth-level variables is shown in Table 1. In total, 565 posterior restorations in primary teeth in 328 children were evaluated. The mean age of children was 8.4 years (SD 2.8). Boys comprised 49.4% of the children evaluated. The mean dmft of the patients was 5.0 (SD 4.0). Regarding the restorations, GIC was the restorative material most frequently used (63.4%), whereas 23.1% of restorations were performed using composites and 13.4% using RMGI. In relation to cavity size, 53.6% were classified as class I and 46.4% as class II. Fig. 1 shows the Kaplan–Meier survival curves over the total period of clinical evaluation. The overall annual failure rate (AFR) after up to 4 years of follow-up was 11.7%. Considering the restorative materials, the AFRs were 9.5% for composite fillings, 12.2% for light-cured glass ionomer restorations and 12.9% for conventional glass ionomer restorations with statistical difference between the materials ( p = 0.014). The Class I restorations had higher survival compared with Class II ( p = 0.016). According to caries experience of patients, the group with moderate caries presented the best survival compared with the high caries group. Table 2 shows the crude and adjusted Cox regression analyses for independent variables and failure of restorations. The adjusted model showed that posterior restorations in children with at least one pulp intervention had a risk of failure more than 1.57 times (1.00–2.45) higher than in children without pulp intervention. Regarding the restorative materials, in comparison with composite restorations, CGICs and light-cured glass ionomer restorations had a risk of failure in 4 years of 1.86 (1.17–2.97) and 1.16 (0.60–2.23), respectively. The type of cavity was associated with the risk of failure over time

Table 1 – Distribution of posterior restorations in primary teeth according individual and tooth-level variables (328 children, 565 restorations). Independent variables

N

%

95% CI

Individual level Sex Male Female

162 166

49.4 50.6

43.9; 54.9 45.1; 56.1

Mother’s school level (yrs) Up to 8 More than 8

167 147

53.2 46.8

47.5; 58.8 41.2; 52.5

Caries experience Moderate caries group High caries group

252 59

81.0 19.0

76.2; 85.2 14.8; 23.8

Pulp intervention No Yes

187 141

57.0 43.0

51.5; 62.4 37.6; 48.5

Tooth level Material Composite resin RMGIC GIC

129 75 354

23.1 13.4 63.4

19.7; 26.8 10.7; 16.6 59.3; 67.4

Type of cavity Class I Class II

303 262

53.6 46.4

49.4; 57.8 42.2; 50.6

in crude analysis, wherever restorations with proximal surface involvement (Class II) had a risk 1.44 times (1.03– 2.00) greater than cavities involving only the occlusal surface (Class I). However this association has lost significance in the adjusted analyses.

4.

Discussion

In this retrospective longitudinal study, the survival of the restorations performed at the Paediatric Dentistry Clinic of the Federal University of Pelotas was evaluated for a period of up to 4 years, with restorations exhibiting good survival rates, depending on the material used. This study provides valuable information regarding the primary teeth posterior restoration longevity and the reasons for failure in a paediatric population with restorations performed under daily life clinical environment. Current literature discusses about the need to restore the decayed primary teeth or if they should be left without restorations.14 Some studies have shown that maintaining cavities opened without biofilm might be a treatment option beyond the conventional restorations or atraumatic restorative treatments (ARTs),15,16 especially considering the time that these teeth remain in the oral cavity. On the other hand, other studies have demonstrated that the presence of caries lesions not restored is the major cause of pain in the primary dentition17 and dental fear.18 There are several approaches to restore primary teeth, and the use of metal crown is still the preferable option in several countries.19 Inclusively, a simplified procedure has been recommended, the Hall technique with the sealing of carious teeth with stainless steel crown.19 However, in Brazil, they are

journal of dentistry 42 (2014) 1248–1254

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Fig. 1 – Kaplan–Meier survival curves. (A) Different materials in posterior primary teeth restorations; (B) type of cavity in posterior primary teeth; (C) curves according caries experience of patients; (D) comparison between patients with and without pulp intervention.

less frequently used, with preference given to adhesive toothcoloured dental materials.20 In the present study, conventional glass ionomer was the restorative material mostly used, being such choice related to the easiness of the technique, requiring fewer steps in relation to resin composite restorations, thus reducing the time of the patient’s chair and also having a low cost.21 Composite resin comprised one quarter of the restorations surveyed, and RMGI was used in 13.4% of the cases. RMGI has a significantly higher cost than conventional GIC, which might reduce its application, despite the better properties when compared with the conventional ones.22 The survival rates after 4 years were 62.2% for composite fillings, 51.2% for light-cured glass ionomer restorations, and 48.4% for conventional glass ionomer restorations, with statistical difference in relation to this variable ( p = 0.014). Composite restorations presented a better survival than GIC, with RMGI presenting an intermediate performance, similar to the other two materials. The main reason to justify this difference is related to the mechanical properties presented by the different materials used. Composite resin presents fillers in their composition, which provide a significant increase in the mechanical properties when compared with GIC, with higher

resistance to wear, higher microhardness, and a smoother surface.23 Overtime, these properties may conduct to a better performance of restorations when submitted to occlusal (mechanical) and chemical stresses, as observed in our study. Also, light curing provides an almost immediate material setting for both composite resin and RMGI, whereas that chemical curing in the GIC might delay the total setting of the material to periods up to 24 h24 that could significantly affect the material behaviour with ageing. Also, when comparing the mechanical properties of RMGICs to GICs, the first ones have generally exhibited better properties, sometimes similar to composite resin,22 which could justify the intermediate survival observed with RMGIC compared with the other two materials. It should be emphasized that in our study, the cavities restored with GIC were mainly performed under cotton roll isolation, especially in patients that were more reticent to dental treatment. A better control of humidity can positively impact in the adhesive procedures, and the presence of saliva could impair the mechanical properties of a material such as GIC where the total setting requires almost 24 h.25 Although some studies have discussed that rubber dam application could improve restoration longevity, a

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journal of dentistry 42 (2014) 1248–1254

Table 2 – Crude (c) and adjusted (a) Hazard Ratios (HR) for independent variables and failure of posterior restorations in primary teeth (Cox regression with shared frailty models). Independent variables

HRc (95% CI)

Sex Male Female

1.00 0.84 (0.56; 1.27)

Mother’s school level (yrs) Up to 8 More than 8

1.00 1.42 (0.93; 2.15)

Caries experience Moderate caries group High caries group

1.00 1.51 (0.91; 2.49)

Pulp intervention No Yes

1.00 1.82 (1.17; 2.84)

Material Composite resin RMGIC GIC

1.00 1.31 (0.68; 2.52) 2.07 (1.30; 3.30)

Type of cavity Class I Class II

1.00 1.44 (1.03; 2.00)

p-Value

HRa (95% CI)

0.411

– –

0.376

0.165 1.00 1.26 (0.91; 1.76)

0.108

0.143 1.00 1.44 (0.88; 2.33)

0.008

0.050 1.00 1.57 (1.00; 2.45)

0.004

Longevity of posterior restorations in primary teeth: results from a paediatric dental clinic.

The aim of this retrospective study was to evaluate the longevity of restorations in the posterior primary teeth of children attending to a public pae...
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